Magnetometer with a light emitting diode

ABSTRACT

A device includes a diamond with one or more nitrogen vacancies, a light emitting diode configured to emit light that travels through the diamond, and a photo sensor configured to sense the light. The device also includes a processor operatively coupled to the photo sensor. The processor is configured to determine, based on the light sensed by the photo sensor, a magnetic field applied to the diamond.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/003,292, filed Jan. 21, 2016, titled “MAGNETOMETER WITH ALIGHT EMITTING DIODE,” and claims the benefit of priority to PCT PatentApplication No. PCT/US2016/014395, which is related to co-pending U.S.application Ser. No. 15/003,281, filed Jan. 21, 2016, titled“MAGNETOMETER WITH LIGHT PIPE,”; U.S. application Ser. No. 15/003,298,filed Jan. 21, 2016, titled “DIAMOND NITROGEN VACANCY SENSOR WITH COMMONRF AND MAGNETIC FIELDS GENERATOR,”; U.S. application Ser. No.15/003,309, filed Jan. 21, 2016, titled “DIAMOND NITROGEN VACANCY SENSORWITH DUAL RF SOURCES,”; and U.S. application Ser. No. 15/003,062, filedJan. 21, 2016, titled “IMPROVED LIGHT COLLECTION FROM DNV SENSORS,” eachof which is incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates, in general, to nitrogen vacancy centersin diamonds. More particularly, the present disclosure relates to usingLEDs to excite nitrogen vacancy centers in diamonds.

BACKGROUND

The following description is provided to assist the understanding of thereader. None of the information provided or references cited is admittedto be prior art. Some diamonds have defects in the crystal structurethat contain nitrogen. A light source can be used to excite the defect.However, many such light sources are large, bulky, expensive, and/orconsume relatively large amounts of power.

SUMMARY

An illustrative device includes a diamond with one or more nitrogenvacancies and a light emitting diode configured to emit light toward thediamond. The device may also include a first photo sensor configured tosense a first portion of the light emitted by the light emitting diode.The first portion of the light may not travel through the diamond. Thedevice may further include a second photo sensor configured to sense asecond portion of the light emitted by the light emitting diode. Thesecond portion of the light may travel through the diamond. The devicemay also include a processor operatively coupled to the first photosensor and a second photo sensor. The processor may be configured tocompare a first signal received from the first photo sensor with asecond signal received from the second photo sensor and determine, basedon the comparison of the first signal and the second signal, a strengthof a magnetic field applied to the diamond.

An illustrative method includes providing power to a light emittingdiode. The light emitting diode may be configured to emit light toward adiamond. The diamond may comprise a nitrogen vacancy. The method mayalso include receiving, at a processor, a first signal from a firstsensor. The first signal may indicate a strength of a frequency of afirst portion of the light emitted by the light emitting diode. Thefirst portion of the light may not travel through the diamond. Themethod may also include receiving, at the processor, a second signalfrom a second sensor. The second signal may indicate a strength of afrequency of a second portion of the light. The second portion of thelight may travel through the diamond. The method may further includecomparing, based on the first signal and the second signal, the strengthof the frequency of the first portion of the light and the strength ofthe frequency of the second portion of the light to determine a strengthof a magnetic field applied to the diamond.

An illustrative method includes emitting, from a light emitting diode, afirst light portion and a second light portion, sensing, at a firstsensor, the first light portion, and sensing, at a second sensor, thesecond light portion, wherein the second light portion traveled througha diamond with a nitrogen vacancy. The method may also include comparingthe first light portion to the second light portion to determine astrength of a magnetic field applied to the diamond.

An illustrative method includes emitting light from a light emittingdiode. The light travels through a diamond with a nitrogen vacancy. Themethod may further include determining, based on a signal from a photosensor that sensed the light, a magnetic field applied to the diamond.

An illustrative method includes emitting light from a light source. Thelight may not be polarized. The light may travel through a diamond withnitrogen vacancies. The method may further include determining, based ona signal from a photo sensor that sensed the light, a magnetic fieldapplied to the diamond.

An illustrative device includes a diamond with one or more nitrogenvacancies, a light emitting diode configured to emit light that travelsthrough the diamond, and a photo sensor configured to sense the light.The device may also include a processor operatively coupled to the photosensor. The processor may be configured to determine, based on the lightsensed by the photo sensor, a magnetic field applied to the diamond.

An illustrative device includes a diamond with one or more nitrogenvacancies, a light source configured to emit light that travels throughthe diamond. The light may not be polarized. The device may furtherinclude a photo sensor configured to sense the light and a processoroperatively coupled to the photo sensor. The processor may be configuredto determine, based on the light sensed by the photo sensor, a magneticfield applied to the diamond.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the following drawings and thedetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a magnetometer in accordance with anillustrative embodiment.

FIG. 2 is an exploded view of a magnetometer in accordance with anillustrative embodiment.

FIG. 3 is a block diagram of a computing device in accordance with anillustrative embodiment.

FIG. 4 is a flow diagram of a method for detecting a magnetic field inaccordance with an illustrative embodiment.

The foregoing and other features of the present disclosure will becomeapparent from the following description and appended claims, taken inconjunction with the accompanying drawings. Understanding that thesedrawings depict only several embodiments in accordance with thedisclosure and are, therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, and designed in awide variety of different configurations, all of which are explicitlycontemplated and make part of this disclosure.

Nitrogen-vacancy centers (NV centers) are defects in a diamond's crystalstructure, which can purposefully be manufactured in synthetic diamonds.In general, when excited by green light and/or microwave radiation, theNV centers cause the diamond to generate red light. When an excited NVcenter diamond is exposed to an external magnetic field the frequency ofthe microwave radiation at which the diamond generates red light and theintensity of the light change. By measuring this change and comparing itto the microwave frequency that the diamond generates red light at whennot in the presence of the external magnetic field, the NV centers canbe used to accurately detect the magnetic field strength.

In many instances, a light source is used to provide light to thediamond. The more light that is transmitted through the diamond, themore light can be detected and analyzed to determine the amount of redlight emitted from the diamond. The amount of red light can be used todetermine the strength of the magnetic field applied to the diamond.Accordingly, in some instances, lasers are used to provide light to thediamond. Lasers can provide concentrated light to the diamond and canfocus the beam of light relatively easily.

However, lasers may not be the most effective light source for allapplications. For example, some lasers produce polarized light. Becausethe axes of the NV centers may not all be oriented in the samedirection, the polarized light from a laser may excite NV centers withaxes oriented in one direction more effectively than NV centers withaxes oriented in other directions. In instances in which sensitivity inall directions (or more than one direction) is desired, non-polarizedlight may be used. The non-polarized light may affect the NV centers ofdifferent orientations (more) uniformly. In such instances, a lightsource such as a light-emitting diode (LED) may be used as the lightsource. In some instances, lasers that produce non-polarized light maybe used. For example, helium-neon (HeNe) lasers can be used.

In some instances, lasers are relatively bulky and large compared toLEDs. In such instances, using LEDs as the light source for amagnetometer using a diamond with NV centers may provide a more compactand versatile sensor. In some instances, lasers user more power toproduce light than do LEDs. In such instances, LEDs may allow a powersource, such as a battery, to last longer, be smaller, and/or provideless power.

FIG. 1 is a block diagram of a magnetometer in accordance with anillustrative embodiment. An illustrative magnetometer 100 includes anLED 105, source light 110, a diamond 115, red light 120, a filter 125,filtered light 130, a photo detector 135, and a radio frequencytransmitter 145. In alternative embodiments, additional, fewer, and/ordifferent elements may be used.

The LED 105 can be used to produce the source light 110. In alternativeembodiments, any suitable light source can be used to produce the sourcelight 110. For example, a light source that produces non-polarized lightcan be used. In embodiments in which an LED is used, any suitable LEDmay be used. For example, the LED 105 can emit primarily green light,primarily blue light, or any other suitable light with a wavelengthshorter than red light.

In some embodiments, the LED 105 emits any suitable light, such as whitelight. The light can pass through one or more filters before enteringthe diamond 115. The filters can filter out light that is not thedesired wavelength.

The source light 110 is emitted by the LED 105. The source light 110 canbe any suitable light. In an illustrative embodiment, the source light110 has a wavelength of between 500 nanometers (nm) and 600 nm. Forexample, the source light 110 can have a wavelength of 532 nm (e.g.,green light), 550 nm, or 518 nm. In some embodiments, the source light110 can be blue (e.g., with a wavelength as low as 450 nm). In yet otherembodiments, the source light 110 can have a wavelength lower than 450nm. In some embodiments, the source light 110 can be any color ofvisible light other than red.

An illustrative diamond 115 includes one or more nitrogen vacancycenters (NV centers). As explained above, each of the NV centers' axescan be oriented in one of multiple directions. In an illustrativeembodiment, each of the NV centers are oriented in one of fourdirections. In some embodiments, the distribution of NV centers with anyparticular axis direction is even throughout the diamond 115. Thediamond 115 can be any suitable size. In some embodiments, the diamond115 is sized such that the source light 110 provides a relatively highlight density. That is, the diamond 115 can be sized such that all oralmost all of the NV centers are excited by the source light 110. Insome instances, the LED 105 emits less light than a laser. In suchinstances, a thinner diamond can be used with the LED 105 to ensure thatall or nearly all of the NV centers are excited. The diamond can be“thinner” in the direction that the source light 110 travels. Thus, thesource light 110 travels a shorter distance through the diamond 115.

A magnet 140 can be used to provide a magnetic field. When the magneticfield is applied to the diamond 115 and light is traveling through thediamond 115, the NV centers can cause the amount of red light emittedfrom the diamond 115 to be changed. For example, when the source light110 is pure green light and there is no magnetic field applied to thediamond 115, then the red light 120, which is emitted from the diamond115, is used as a baseline level of red light 120. When there is amagnetic field applied to the diamond 115, such as via the magnet 140,the amount of red light 120 varies in intensity. Thus, by monitoring theamount of red light from a baseline (e.g., no magnetic field applied tothe diamond 115) in the red light 120, a magnetic field applied to thediamond 115 can be measured. In some instances, the red light 120emitted from the diamond 115 can be any suitable wavelength.

The radio frequency transmitter 145 can be used to transmit radio wavesto the diamond 115. The amount of red light emitted from the diamond 115changes based on the frequency of the radio waves absorbed by thediamond 115. Thus, by modulating the frequency of the radio wavesemitted from the radio frequency transmitter 145 the amount of red lightsensed by the photo detector 135 may change. By monitoring the amount ofred light sensed by the photo detector 135 relative to the frequency ofthe radio waves emitted by the radio frequency transmitter 145, thestrength of the magnetic field applied to the diamond 115 by the magnet140 can be determined.

In an illustrative embodiment, a photo detector 135 is used to receivethe light emitted from the diamond 115. The photo detector 135 can beany suitable sensor configured to analyze light emitted from the diamond115. For example, the photo detector 135 can be used to determine theamount of red light in the red light 120.

As illustrated in FIG. 1, some embodiments include a filter 125. Thefilter 125 can be configured to filter the red light 120. For example,the filter 125 can be a red filter that permits red light to passthrough the filter 125 but blocks some or all of non-red light frompassing through the filter 125. In alternative embodiments, any suitablefilter 125 can be used. In some embodiments, the filter 125 is not used.In embodiments that include the filter 125, the red light 120 emittedfrom the diamond 115 passes through the filter 125, and the filteredlight 130 (which is emitted from the filter 125) travels to the photodetector 135. In embodiments in which a filter 125 is used, greatersensitivity may be achieved because the photo detector 135 detects onlythe light of interest (e.g., red light) and other light (e.g., greenlight, blue light, etc.) does not affect the sensitivity of the photodetector 135.

FIG. 2 is an exploded view of a magnetometer in accordance with anillustrative embodiment. An illustrative magnetometer 200 includes anLED 205, a housing 210, a source light photo sensor 215, a mirror tubeassembly 220, electromagnetic glass 225, a concentrator 230, retainingrings 235, a diamond assembly 240, a concentrator 245, a modulated lightphoto sensor 250, a sensor plate 255, and a lens tube coupler 260. Inalternative embodiments, additional, fewer, and/or different elementsmay be used. Additionally, the embodiment illustrated in FIG. 2 is meantto be illustrative only and not meant to be limiting with respect to theorientation, size, or location of elements.

An illustrative LED 205 includes a heat sink that is configured todissipate into the environment heat created by the LED 205. In theembodiment illustrated in FIG. 2, at least a portion of the LED 205(e.g., a cylindrical portion) fits within the housing 210. Adjacent tothe LED 205 within the housing 210 is the mirror tube assembly 220. Themirror tube assembly 220 is configured to focus the light from the LED205 into a concentrated beam.

The source light photo sensor 215 is configured to receive a portion ofthe light emitted from the LED 205. In some embodiments, the sourcelight photo sensor 215 can include a green filter. In such embodiments,the source light photo sensor 215 receives mostly or all green light. Inembodiments in which the source light photo sensor 215 is used, theamount of green light sensed by the source light photo sensor 215 can becompared to the amount of red light sensed by the modulated photo sensor250 to determine the magnitude of the magnetic field applied to thediamond assembly 240. As discussed above, in some embodiments, thesource light photo sensor 215 may not be used. In such embodiments, theamount of red light sensed by the modulated photo sensor 250 can becompared to a baseline amount of red light to determine the magnitude ofthe magnetic field applied to the diamond assembly 240.

In some embodiments, such as those that use the source light photosensor 215, electromagnetic glass 225 can be located between the sourcelight photo sensor 215 and the diamond assembly 240. In someembodiments, the diamond assembly 240 can emit electromagneticinterference (EMI) signals. In some instances, the source light photosensor 215 can be sensitive to EMI signals. That is, in such instances,the source light photo sensor 215 performs better when there is less EMIaffecting the source light photo sensor 215. The electromagnetic glass225 can allow light to pass through the electromagnetic glass 225, butinhibit transmission of electromagnetic signals. Any suitableelectromagnetic glass 225 can be used. In alternative embodiments, anysuitable EMI attenuator can be used.

The concentrator 230 can be configured to concentrate light from themirror tube assembly 220 (and/or the electromagnetic glass 225) into amore narrow beam of light. The concentrator 230 can be any suitableshape, such as parabolic. The diamond assembly 240 can include a diamondwith one or more NV centers. The concentrator 230 can concentrate lightfrom the LED 205 into a beam of light with a cross-sectional area thatis similar to the cross-sectional area of the diamond. That is, thelight from the LED 205 can be concentrated to most effectively flood thediamond with the light such that as much of the light as possible fromthe LED 205 passes through the diamond and/or such that as many NVcenters as possible are excited by the light. The concentrator 230 mayinclude a ring mount that is configured to hold the concentrator 230 ata secure location within the housing 210.

The diamond assembly 240 can include any suitable components. Forexample, as mentioned above, the diamond assembly 240 can include adiamond. The diamond can be located at the center of the diamondassembly 240. The diamond assembly 240 may also include one or morecircuit boards that are configured to modulate electromagnetic signalsapplied to the diamond. In an illustrative embodiment, the diamondassembly 240 includes a Helmholtz coil. For example, a three-dimensionalHelmholtz coil can be used counteract or cancel unwanted magnetic fieldsfrom affecting the diamond. In an illustrative embodiment, the circuitboards or other electronics can emit EMI signals. In some embodiments,the diamond assembly 240 includes a red filter that allows red lightemitted from the diamond to pass through to the modulated photo sensor250. In alternative embodiments, the red filter can be located at anysuitable location between the diamond and the modulated photo sensor250. In yet other embodiments, the red filter may not be used.

In some embodiments, the retaining rings 235 can be used to hold one ormore of the elements of the magnetometer 200 within the housing 210.Although FIG. 2 illustrates two retaining rings 235, any suitable numberof retaining rings 235 may be used. In some embodiments, the retainingrings 235 may not be used.

Similar to the concentrator 230, the concentrator 245 is configured toconcentrate light emitted from the diamond assembly 240 into a morenarrow beam. For example, the concentrator 230 can be configured toconcentrate light into a beam that has the same or a similarcross-sectional area as the modulated photo sensor 250. The concentrator245 can be configured to focus as much light as possible from thediamond assembly 240 to the modulated photo sensor 250. By increasingthe amount of light emitted from the diamond assembly 240 that is sensedby the modulated photo sensor 250, the sensitivity of the magnetometer200 can be increased.

As mentioned above, electromagnetic glass 225 can be located between thediamond assembly 240 and the modulated photo sensor 250 to shield themodulated photo sensor 250 from EMI signals emitted from the diamondassembly 240. The sensor plate 255 can be used to hold the modulatedphoto sensor 250 in place such that the modulated photo sensor 250receives the concentrated light beam from the concentrator 245 (and/orthe diamond assembly 240). A lens tube coupler 260 may be used as an endcap to the housing 210, thereby holding the various elements in placeinside the housing 210.

FIG. 3 is a block diagram of a computing device in accordance with anillustrative embodiment. An illustrative computing device 300 includes amemory 310, a processor 305, a transceiver 315, a user interface 320, apower source 325, and an magnetometer 330. In alternative embodiments,additional, fewer, and/or different elements may be used. The computingdevice 300 can be any suitable device described herein. For example, thecomputing device 300 can be a desktop computer, a laptop computer, asmartphone, a specialized computing device, etc. The computing device300 can be used to implement one or more of the methods describedherein.

In an illustrative embodiment, the memory 310 is an electronic holdingplace or storage for information so that the information can be accessedby the processor 305. The memory 310 can include, but is not limited to,any type of random access memory (RAM), any type of read only memory(ROM), any type of flash memory, etc. such as magnetic storage devices(e.g., hard disk, floppy disk, magnetic strips, etc.), optical disks(e.g., compact disk (CD), digital versatile disk (DVD), etc.), smartcards, flash memory devices, etc. The computing device 300 may have oneor more computer-readable media that use the same or a different memorymedia technology. The computing device 300 may have one or more drivesthat support the loading of a memory medium such as a CD, a DVD, a flashmemory card, etc.

In an illustrative embodiment, the processor 305 executes instructions.The instructions may be carried out by a special purpose computer, logiccircuits, or hardware circuits. The processor 305 may be implemented inhardware, firmware, software, or any combination thereof. The term“execution” is, for example, the process of running an application orthe carrying out of the operation called for by an instruction. Theinstructions may be written using one or more programming language,scripting language, assembly language, etc. The processor 305 executesan instruction, meaning that it performs the operations called for bythat instruction. The processor 305 operably couples with the userinterface 320, the transceiver 315, the memory 310, etc. to receive, tosend, and to process information and to control the operations of thecomputing device 300. The processor 305 may retrieve a set ofinstructions from a permanent memory device such as a ROM device andcopy the instructions in an executable form to a temporary memory devicethat is generally some form of RAM. An illustrative computing device 300may include a plurality of processors that use the same or a differentprocessing technology. In an illustrative embodiment, the instructionsmay be stored in memory 310.

In an illustrative embodiment, the transceiver 315 is configured toreceive and/or transmit information. In some embodiments, thetransceiver 315 communicates information via a wired connection, such asan Ethernet connection, one or more twisted pair wires, coaxial cables,fiber optic cables, etc. In some embodiments, the transceiver 315communicates information via a wireless connection using microwaves,infrared waves, radio waves, spread spectrum technologies, satellites,etc. The transceiver 315 can be configured to communicate with anotherdevice using cellular networks, local area networks, wide area networks,the Internet, etc. In some embodiments, one or more of the elements ofthe computing device 300 communicate via wired or wirelesscommunications. In some embodiments, the transceiver 315 provides aninterface for presenting information from the computing device 300 toexternal systems, users, or memory. For example, the transceiver 315 mayinclude an interface to a display, a printer, a speaker, etc. In anillustrative embodiment, the transceiver 315 may also includealarm/indicator lights, a network interface, a disk drive, a computermemory device, etc. In an illustrative embodiment, the transceiver 315can receive information from external systems, users, memory, etc.

In an illustrative embodiment, the user interface 320 is configured toreceive and/or provide information from/to a user. The user interface320 can be any suitable user interface. The user interface 320 can be aninterface for receiving user input and/or machine instructions for entryinto the computing device 300. The user interface 320 may use variousinput technologies including, but not limited to, a keyboard, a stylusand/or touch screen, a mouse, a track ball, a keypad, a microphone,voice recognition, motion recognition, disk drives, remote controllers,input ports, one or more buttons, dials, joysticks, etc. to allow anexternal source, such as a user, to enter information into the computingdevice 300. The user interface 320 can be used to navigate menus, adjustoptions, adjust settings, adjust display, etc.

The user interface 320 can be configured to provide an interface forpresenting information from the computing device 300 to externalsystems, users, memory, etc. For example, the user interface 320 caninclude an interface for a display, a printer, a speaker,alarm/indicator lights, a network interface, a disk drive, a computermemory device, etc. The user interface 320 can include a color display,a cathode-ray tube (CRT), a liquid crystal display (LCD), a plasmadisplay, an organic light-emitting diode (OLED) display, etc.

In an illustrative embodiment, the power source 325 is configured toprovide electrical power to one or more elements of the computing device300. In some embodiments, the power source 325 includes an alternatingpower source, such as available line voltage (e.g., 120 Voltsalternating current at 60 Hertz in the United States). The power source325 can include one or more transformers, rectifiers, etc. to convertelectrical power into power useable by the one or more elements of thecomputing device 300, such as 1.5 Volts, 8 Volts, 12 Volts, 24 Volts,etc. The power source 325 can include one or more batteries.

In an illustrative embodiment, the computing device 300 includes amagnetometer 330. In some embodiments, magnetometer 330 is anindependent device and is not integrated into the computing device 300.The magnetometer 330 can be configured to measure magnetic fields. Forexample, the magnetometer 330 can be the magnetometer 100, themagnetometer 200, or any suitable magnetometer. The magnetometer 330 cancommunicate with one or more of the other components of the computingdevice 300 such as the processor 305, the memory 310, etc. For example,one or more photo detectors of the magnetometer 330 can transmit asignal to the processor 305 indicating an amount of light detected bythe respective photo detector. The signal can be used to determine thestrength and/or direction of the magnetic field applied to the diamondof the magnetometer 330. In alternative embodiments, any suitablecomponent of the magnetometer 330 can transmit a signal to othercomponents of the 300 (e.g., the processor 305), such as a Helmholtzcoil, a source light photo detector, one or more modulated light photodetectors, a light source, etc.

FIG. 4 is a flow diagram of a method for detecting a magnetic field inaccordance with an illustrative embodiment. In alternative embodiments,additional, fewer, and/or different operations may be performed. Also,the use of a flow diagram and arrows is not meant to be limiting withrespect to the order or flow of operations.

For example, in some embodiments, one or more of the operations may beperformed simultaneously.

In an operation 405, power is provided to a light emitting diode (LED).Any suitable amount of power can be provided. For example, a 5milli-Watt (mW) LED can be used. The LED can be powered by two or moreAA batteries. In alternative embodiments, the LED can use more or lesspower. In some embodiments, the amount of power provided to the LED ismodulated based on a particular application. In some embodiments, theoperation 205 includes providing pulsed power to the LED to cause theLED to alternately lighten and darken. In such embodiments, any suitablefrequency and/or pattern can be used. In alternative embodiments, theoperation 405 can include causing any suitable device to emitnon-polarized light.

In an operation 410, light emitted from the LED is sensed. Sensing thelight from the LED can include using a photo detector. The operation 410can include determining an amount of green light emitted from the LED.In some embodiments, the operation 410 is not performed.

In an operation 415, light from the LED is focused into a diamond. Thediamond can include one or more NV centers. The light can be focused asto excite as many of the NV centers as possible with the light from theLED. Any suitable focusing method can be used. For example, lenses orlight pipes can be used to focus light from the LED to the diamond.

In an operation 420, light from the diamond is focused to a photodetector. Light from the LED passes through the diamond, is modulated bythe diamond, and is emitted from the diamond. The light emitted from thediamond is focused to a detector such that as much light emitted fromthe diamond as possible is detected by the photo detector. In anoperation 425, the light from the diamond is sensed by the photodetector. In an illustrative embodiment, the operation 425 includesdetermining the amount of red light emitted from the diamond.

In an operation 430, a magnetic field applied to the diamond isdetermined. In embodiments in which operation 410 is performed, theamount of red light emitted by the diamond is compared to the amount ofgreen light emitted from the LED to determine the magnetic field. Inembodiments, in which operation 410 is not performed, the amount of redlight emitted from the diamond is compared to a baseline quantity of redlight. In alternative embodiments, any suitable method of determiningthe magnetic field applied to the diamond can be used.

In an illustrative embodiment, noise in the light emitted from the LEDcan be compensated for. In such an embodiment, noise in the lightemitted from the LED can be detected by a photo detector, such as thephoto detector used for the operation 410. Noise in the light emittedfrom the LED passes through the diamond and is sensed by the photodetector that senses light emitted from the diamond, such as the photodetector used for the operation 425. In an illustrative embodiment,amount of light detected in the operation 410 is subtracted from thelight detected in the operation 430. The result of the subtraction isthe changes in the light caused by the diamond.

In an illustrative embodiment, any of the operations described hereincan be implemented at least in part as computer-readable instructionsstored on a computer-readable memory. Upon execution of thecomputer-readable instructions by a processor, the computer-readableinstructions can cause a node to perform the operations.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected,” or“operably coupled,” to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable,” to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.” Further, unlessotherwise noted, the use of the words “approximate,” “about,” “around,”“substantially,” etc., mean plus or minus ten percent.

The foregoing description of illustrative embodiments has been presentedfor purposes of illustration and of description. It is not intended tobe exhaustive or limiting with respect to the precise form disclosed,and modifications and variations are possible in light of the aboveteachings or may be acquired from practice of the disclosed embodiments.It is intended that the scope of the invention be defined by the claimsappended hereto and their equivalents.

What is claimed is:
 1. A method comprising: providing power to a lightemitting diode, wherein the light emitting diode is configured to emitlight toward a diamond, wherein the diamond comprises a nitrogenvacancy; receiving, at a processor, a first signal from a first sensor,wherein the first signal indicates a strength of a frequency of a firstportion of the light emitted by the light emitting diode, wherein thefirst portion of the light does not travel through the diamond;receiving, at the processor, a second signal from a second sensor,wherein the second signal indicates a strength of a frequency of asecond portion of the light, wherein the second portion of the lighttravels through the diamond; and comparing, based on the first signaland the second signal, the strength of the frequency of the firstportion of the light and the strength of the frequency of the secondportion of the light to determine a strength of a magnetic field appliedto the diamond.
 2. The method of claim 1, wherein the first portion ofthe light travels through a first filter, and wherein light travelingthrough the first filter and to the first photo sensor is substantiallygreen.
 3. The method of claim 1, wherein the second portion of the lighttravels through a second filter, and wherein light traveling through thesecond filter and to the second photo sensor is substantially red. 4.The method of claim 1, wherein the light emitted from the light emittingdiode is substantially green.
 5. The method of claim 1, furthercomprising: detecting noise in the light emitted from the light emittingdiode, and compensating for noise in the second portion of the lightbased on the detected noise in the light emitted from the light emittingdiode.